Washington (CNN) – As the Senate begins getting down to the business on Friday of whether to defund the health care law backed by President Barack Obama, a national Republican political committee cautions Democratic incumbents facing tough reelection fights.

"Today, Democrats may have one last opportunity to save their Senate seat by opposing an amendment to fund Obamacare," reads a release the National Republican Senatorial Committee is sending to five states that have a Democratic senator and large numbers of conservatives.FULL POST